Pressure control well cementation system and method

Abstract

The invention discloses a pressure control well cementation system and method. The system comprises an automatic throttling unit, an automatic slurry supplementing and pressurizing unit and a control center. Wherein the automatic throttling unit is used for being arranged between a well mouth and a mud tank so as to control the back pressure of the well mouth by adjusting the valve opening degree of the throttling valve; the automatic slurry supplementing and pressurizing unit is used for being communicated with a connecting pipeline between a well mouth and the automatic throttling unit so as to control well mouth back pressure by compensating fluid flow for the system. The control center is used for controlling the automatic throttling unit to adjust the valve opening degree of the throttling valve and / or controlling the automatic slurry supplementing and pressurizing unit to adjust the output fluid flow so as to control the back pressure of the wellhead based on the target fluid parameters of the wellhead and the parameter deviation of the corresponding actually-measured fluid parameters. The fluid parameters comprise pressure or fluid flow, and the actually-measured fluid parameters comprise actually-measured pressure of one end, close to the wellhead, of a throttling valve of the automatic throttling unit or actually-measured fluid flow of the output end of the automatic throttling unit. And pressure control in the whole well cementation process can be achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of controlled pressure cementing, and in particular to a controlled pressure cementing system and method. Background Art

[0002] With the continuous deepening of exploration and development, oil and gas drilling has gradually developed from deep wells to ultra-deep wells. The formation temperature and pressure are getting higher and higher, and the rock properties are becoming more complex, which makes the wellbore stability more sensitive and fragile. In particular, facing more and more high-temperature and high-pressure complex ultra-deep well drilling tasks, the existing safety control technology has been difficult to effectively respond to. Downhole complexities such as leakage and collapse occur frequently, drilling efficiency is greatly reduced, and the comprehensive drilling cost is significantly increased. Taking a certain oil field as an example, the drilling speed of ultra-deep wells above 7000m is only 1 / 4 to 1 / 2 of that of conventional deep wells (4500-6000m), and non-production time and drilling costs are doubled.

[0003] During oil and gas drilling, the use of managed pressure drilling technology can effectively solve the downhole complexities such as gushing, leakage, collapse, and sticking caused by complex pressure conditions such as narrow density windows during drilling, thereby protecting the reservoir during drilling and improving the overall drilling efficiency. Existing managed pressure drilling equipment generally includes three major components: an automatic throttling control manifold, a back pressure pump, and a control center.

[0004] However, since high-density drilling fluid and high-density cement slurry are often used for cementing operations, there is a greater risk of leaking the formation. In addition, in the event of complex downhole conditions such as gushing and leakage, the solidification of cement slurry during cementing operations will be affected, which will in turn affect the sealing effect of the wellbore. Studies on existing technologies have shown that the use of controlled pressure cementing technology based on controlled pressure drilling technology is a method to solve the technical difficulties of cementing under complex geological conditions, that is, the bottom hole pressure must also be controlled during the cementing process to ensure the balance between the bottom hole pressure and the formation pressure under the best possible conditions, avoid leaking the formation, and achieve safe and reliable cementing operations. Summary of the invention

[0005] The inventors of the present application have discovered that due to the complexity of the cementing operation process, a higher demand is placed on bottom hole pressure control, and the back pressure pump output flow of existing pressure controlled drilling equipment is fixed, and wellhead back pressure can only be controlled by adjusting the valve opening of the throttle valve of the throttle control manifold. However, the valve opening adjustment range of the throttle valve is limited, and when the opening is adjusted to a smaller value, the control accuracy fluctuates greatly, which cannot meet the needs of pressure controlled cementing operations in a complex formation pressure system environment.

[0006] In view of the above problems, the present invention is proposed to provide a controlled pressure cementing system and method that overcomes the above problems or at least partially solves the above problems.

[0007] The embodiment of the present invention provides a controlled pressure cementing system, including: an automatic throttling unit, an automatic grouting and pressurizing unit, and a control center;

[0008] The automatic throttling unit is used to be arranged between the wellhead and the mud tank to control the wellhead back pressure by adjusting the valve opening of the throttling valve;

[0009] The automatic grouting and pressurizing unit is used to communicate with the connecting pipeline between the wellhead and the automatic throttling unit to control the wellhead back pressure by compensating the system fluid flow;

[0010] The control center is used to control the automatic throttling unit to adjust the valve opening of the throttling valve, and / or control the automatic grouting and pressurization unit to adjust the output fluid flow rate to control the wellhead back pressure based on the target fluid parameter at the wellhead and the parameter deviation from the corresponding measured fluid parameter; the fluid parameter includes: pressure or fluid flow rate, and correspondingly, the measured fluid parameter includes: the measured pressure at one end of the throttling valve of the automatic throttling unit close to the wellhead or the measured fluid flow rate at the output end of the automatic throttling unit.

[0011] In an optional embodiment, the control center is used to control the automatic throttling unit to adjust the valve opening of the throttling valve and / or control the automatic grouting and boosting unit to adjust the output fluid flow rate based on the parameter deviation between the target fluid parameter at the wellhead and the corresponding measured fluid parameter; including:

[0012] When the measured fluid parameter is less than the target fluid parameter of the wellhead: the control center is used to control the automatic throttling unit to adjust the valve opening of the throttling valve, and / or control the automatic grouting and boosting unit to adjust the output fluid flow rate based on the target fluid parameter of the wellhead and the parameter deviation range of the corresponding measured fluid parameter;

[0013] When the measured fluid parameter is greater than the target fluid parameter of the wellhead:

[0014] If the automatic grouting and pressurizing unit is in a state of supplementing fluid flow, the control center is used to control the automatic throttling unit to adjust the valve opening of the throttling valve and / or control the automatic grouting and pressurizing unit to adjust the output fluid flow based on the target fluid parameter of the wellhead and the parameter deviation range of the corresponding measured fluid parameter;

[0015] If the automatic grouting and pressurizing unit is in a state of not replenishing fluid flow, the control center is used to control the automatic throttling unit to adjust the valve opening of the throttling valve based on the target fluid parameter of the wellhead and the parameter deviation range of the corresponding measured fluid parameter.

[0016] In an optional embodiment, when the measured fluid parameter is less than the target fluid parameter at the wellhead: the control center is used to control the automatic throttling unit to adjust the valve opening of the throttling valve and / or control the automatic grouting and boosting unit to adjust the output fluid flow rate based on the target fluid parameter at the wellhead and the parameter deviation range of the corresponding measured fluid parameter; including: when the measured fluid parameter is less than the target fluid parameter at the wellhead: the control center is used to,

[0017] When the parameter deviation between the target fluid parameter at the wellhead and the corresponding measured fluid parameter is greater than a first preset deviation threshold, the throttle valve of the automatic throttling unit is controlled to be at a preset opening, the measured fluid parameter when the valve is at the preset opening is obtained, and based on the parameter deviation between the measured fluid parameter and the target fluid parameter at the wellhead at this time, the automatic grouting and pressurization unit is controlled to increase the output fluid flow rate;

[0018] When the parameter deviation is greater than a second preset deviation threshold and less than or equal to a first preset deviation threshold, the valve opening of the throttle valve is controlled based on the parameter deviation, or the valve opening of the throttle valve is controlled to remain unchanged, and the automatic grouting and boosting unit is controlled based on the parameter deviation to increase the output fluid flow rate;

[0019] When the parameter deviation is less than or equal to the second preset parameter deviation, the valve opening of the automatic throttling unit and the fluid flow output by the automatic grouting and pressurizing unit are controlled to remain unchanged.

[0020] In an optional embodiment, when the measured fluid parameter is greater than the target fluid parameter of the wellhead, if the automatic grouting and pressurizing unit is in a state of supplementing fluid flow, the control center is used to control the automatic throttling unit to adjust the valve opening of the throttling valve based on the target fluid parameter of the wellhead and the parameter deviation range of the corresponding measured fluid parameter, and / or control the automatic grouting and pressurizing unit to adjust the output fluid flow; if the automatic grouting and pressurizing unit is in a state of not supplementing fluid flow: the control center is used to control the automatic throttling unit to adjust the valve opening of the throttling valve based on the parameter deviation range; including:

[0021] When the measured fluid parameter is greater than the target fluid parameter of the wellhead:

[0022] The automatic grouting and boosting unit is in the state of supplementing fluid flow:

[0023] The control center is used to control the automatic grouting and pressurizing unit to reduce the output fluid flow rate and control the valve opening of the automatic throttling unit to a maximum value based on the parameter deviation between the target fluid parameter at the wellhead and the corresponding measured fluid parameter when the parameter deviation between the target fluid parameter at the wellhead and the corresponding measured fluid parameter is greater than a third preset deviation threshold;

[0024] When the parameter deviation is greater than a fourth preset deviation threshold and less than or equal to a third preset deviation threshold, controlling the valve opening of the automatic throttling unit based on the parameter deviation, or controlling the automatic grouting and pressurizing unit to reduce the output fluid flow;

[0025] When the parameter deviation is less than or equal to the fourth preset parameter deviation threshold, the valve opening of the automatic throttling unit and the fluid flow rate output by the automatic grouting and pressurizing unit are controlled to remain unchanged;

[0026] The automatic grouting booster unit is in the state of not replenishing fluid flow:

[0027] The control center is used to control the valve opening of the automatic throttling unit to be the maximum value when the parameter deviation is greater than a fifth preset deviation threshold;

[0028] When the parameter deviation is greater than the sixth preset deviation threshold and less than or equal to the fifth preset deviation threshold, the valve opening of the automatic throttling unit is controlled based on the parameter deviation;

[0029] When the parameter deviation is less than or equal to the sixth preset deviation threshold, the valve opening of the automatic throttling unit is controlled to remain unchanged.

[0030] In an optional embodiment, the automatic grouting and pressurizing unit comprises: a hydraulic component, an electrical control component and a piston pump;

[0031] The electrical control component is electrically connected to the control center to receive a control instruction from the control center, and controls the hydraulic component to drive the piston pump to work and output a fluid flow based on the control instruction.

[0032] In an optional embodiment, the automatic grouting and pressurizing unit also includes a dynamic monitoring module to monitor the outlet pressure, outlet flow, temperature, voltage, and current data of the automatic grouting and pressurizing unit in real time, and issue an early warning reminder when the monitoring data is abnormal.

[0033] In an optional embodiment, the automatic grouting and pressurizing unit further includes: a first human-computer interaction module;

[0034] The first human-machine interaction module is used to control the automatic grouting and pressurization based on the operator's operating instructions, record and analyze the real-time monitoring data, and issue an alarm and perform fault diagnosis when the real-time monitoring data is abnormal;

[0035] Correspondingly, the electrical control component is also used to control the hydraulic component to drive the piston pump to work and output fluid flow based on the control instruction of the first human-machine interaction module.

[0036] In an optional embodiment, the automatic throttling unit comprises: a modular straight-through skid and an automatic throttling skid assembly, wherein the automatic throttling skid assembly comprises at least one automatic throttling skid;

[0037] The modular straight-through skid is arranged in parallel with the automatic throttling skid assembly;

[0038] Furthermore, when the automatic throttling skid assembly includes two or more automatic throttling skids, the automatic throttling skids are arranged in parallel.

[0039] In an optional embodiment, the modular automatic throttling skid comprises: an electric control cabinet and an electric throttling valve arranged on the throttling pipeline;

[0040] The electric control cabinet is used to control the valve opening of the electric throttle valve based on the control instruction of the control center.

[0041] In an optional embodiment, the automatic throttling skid further includes: an air control cabinet, a first pressure sensor, an air control flat valve, a first needle valve, a manual valve, a second pressure sensor, a filter, a second needle valve and a mass flow meter sequentially arranged on the throttling pipeline;

[0042] The gas control cabinet is used to control the opening and closing of the gas-controlled flat valve based on the control instructions of the control center;

[0043] The electric throttle valve is arranged between the air-controlled flat valve and the first needle valve, and the pressure detected by the first pressure sensor is used as the measured pressure, and the mass flow meter is used to detect the fluid flow rate as the measured fluid flow rate.

[0044] In an optional embodiment, the modular straight-through skid includes: a main pipeline and a first pipeline and a second pipeline connected to the main pipeline, the first pipeline and the second pipeline are respectively used to communicate with the inlet and outlet of the throttling pipeline of the modular automatic throttling skid, and the main pipeline, the first pipeline and the second pipeline are respectively provided with flat valves for controlling the opening and closing of the pipeline.

[0045] In an optional embodiment, the automatic throttling unit further includes: a second human-computer interaction module;

[0046] The second human-computer interaction module is used to control the automatic throttling unit based on the operator's operating instructions, record and analyze the real-time monitoring data, and issue an alarm and perform fault diagnosis when the real-time monitoring data is abnormal;

[0047] Correspondingly, the gas control cabinet is also used to control the opening and closing of the gas-controlled flat valve based on the control instructions of the second human-machine interaction module;

[0048] The electric control cabinet is also used to control the valve opening of the electric throttle valve based on the control instruction of the second human-machine interaction module.

[0049] In an optional embodiment, the control center is also used to provide a safety protection mode and / or an expert mode;

[0050] The safety protection mode is used to give an early warning when the measured pressure is abnormal, and to perform one or more of the following controls:

[0051] Control the electric throttle valve opening of the currently used automatic throttle skid to the maximum;

[0052] When the flat valve of the modular direct-flow skid is a pneumatically controlled flat valve, the pneumatic flat valve of the modular direct-flow skid is controlled to open;

[0053] When there are multiple automatic throttling skids, the pneumatically controlled flat valves of other automatic throttling skids are controlled to open;

[0054] The expert mode is used to enable operation authority based on the authority instruction input by the operator, and when the operation authority is enabled, perform related operations based on the control instruction input by the operator, and the related operations include: conventional operations in non-expert mode and designated operations in expert mode; wherein the designated operations include: closing the electric-controlled throttle valve and / or the pneumatic-controlled flat valve.

[0055] In an optional embodiment, the pressure-controlled cementing system provided by the embodiment of the present invention further includes: an inlet monitoring unit;

[0056] The inlet monitoring unit is used to be connected to the wellhead entry pipe string to monitor the pressure and flow of the fluid entering the wellbore in real time.

[0057] In an optional embodiment, the controlled pressure cementing system provided by the embodiment of the present invention further includes: a cementing pump and a drilling pump;

[0058] The drilling pump and cementing pump are respectively connected to the wellhead entry pipe string;

[0059] The inlet measurement unit comprises: a first measurement pipeline and a first flow meter and a third pressure sensor arranged thereon, a second measurement pipeline and a second flow meter and a fourth pressure sensor arranged thereon;

[0060] The first measuring pipeline is used to connect with the connecting pipeline between the cementing pump and the wellhead tubing string; the second measuring pipeline is used to connect with the connecting pipeline between the drilling pump and the wellhead tubing string.

[0061] Based on the same inventive concept, an embodiment of the present invention further provides a controlled pressure cementing method, comprising:

[0062] Obtaining target fluid parameters at the wellhead and corresponding measured fluid parameters; the fluid parameters include: pressure and / or fluid flow rate, and correspondingly, the measured fluid parameters include: the measured pressure at one end of the throttle valve of the automatic throttling unit close to the wellhead, and / or the fluid flow rate at the output end of the automatic throttling unit;

[0063] Based on the parameter deviation between the target fluid parameter of the wellhead and the corresponding measured fluid parameter, the automatic throttling unit is controlled to adjust the opening of the valve, and / or the automatic grouting and pressurizing unit is controlled to adjust the output fluid flow rate to control the wellhead back pressure.

[0064] In an optional embodiment, based on the parameter deviation between the target fluid parameter at the wellhead and the measured fluid parameter, controlling the automatic throttling unit to adjust the valve opening, and / or controlling the automatic grouting and pressurizing unit to operate, comprises:

[0065] In the case where the measured fluid parameter is less than the target fluid parameter of the wellhead, based on the target fluid parameter of the wellhead and the parameter deviation range of the corresponding measured fluid parameter, the automatic throttling unit is controlled to adjust the valve opening of the throttling valve, and / or the automatic grouting and pressurizing unit is controlled to adjust the output fluid flow rate;

[0066] In the case where the measured fluid parameter is greater than the target fluid parameter of the wellhead, if the automatic grouting and pressurization unit is in a state of supplementing fluid flow, the automatic throttling unit is controlled to adjust the valve opening of the throttling valve and / or the automatic grouting and pressurization unit is controlled to adjust the output fluid flow based on the target fluid parameter of the wellhead and the parameter deviation range of the corresponding measured fluid parameter; if the automatic grouting and pressurization unit is in a state of not supplementing fluid flow, the automatic throttling unit is controlled to adjust the valve opening of the throttling valve based on the parameter deviation range.

[0067] In an optional embodiment, when the measured fluid parameter is less than the target fluid parameter of the wellhead, based on the target fluid parameter of the wellhead and the parameter deviation range of the corresponding measured fluid parameter, the automatic throttling unit is controlled to adjust the valve opening of the throttling valve, and / or the automatic grouting and pressurizing unit is controlled to adjust the output fluid flow rate, including: when the measured fluid parameter is less than the target fluid parameter of the wellhead:

[0068] If the parameter deviation between the target fluid parameter at the wellhead and the corresponding measured fluid parameter is greater than a first preset deviation threshold, the throttle valve of the automatic throttling unit is controlled to be at a preset opening, the measured fluid parameter when the valve is at the preset opening is obtained, and based on the parameter deviation between the measured fluid parameter and the target fluid parameter at the wellhead, the automatic grouting and pressurization unit is controlled to increase the output fluid flow rate;

[0069] If the parameter deviation is greater than a second preset deviation threshold and less than or equal to the first preset deviation threshold, the valve opening of the throttle valve is controlled based on the parameter deviation, or the valve opening of the throttle valve is controlled to remain unchanged, and the automatic grouting and boosting unit is controlled to increase the output fluid flow rate based on the parameter deviation;

[0070] If the parameter deviation is less than or equal to the second preset parameter deviation, the valve opening of the automatic throttling unit and the fluid flow output by the automatic grouting and pressurizing unit are kept unchanged.

[0071] In an optional embodiment, when the measured fluid parameter is greater than the target fluid parameter of the wellhead, if the automatic grouting and pressurizing unit is in a state of supplementing fluid flow, based on the target fluid parameter of the wellhead and the parameter deviation range of the corresponding measured fluid parameter, the automatic throttling unit is controlled to adjust the valve opening of the throttling valve, and / or the automatic grouting and pressurizing unit is controlled to adjust the output fluid flow; if the automatic grouting and pressurizing unit is in a state of not supplementing fluid flow: the automatic throttling unit is controlled to adjust the valve opening of the throttling valve based on the parameter deviation range; including: when the measured fluid parameter is greater than the target fluid parameter of the wellhead:

[0072] The automatic grouting and boosting unit is in the state of supplementing fluid flow:

[0073] If the parameter deviation between the target fluid parameter of the wellhead and the corresponding measured fluid parameter is greater than a third preset deviation threshold, based on the parameter deviation between the target fluid parameter of the wellhead and the corresponding measured fluid parameter, the automatic grouting and pressurizing unit is controlled to reduce the output fluid flow rate, and the valve opening of the automatic throttling unit is controlled to be the maximum value;

[0074] If the parameter deviation is greater than a fourth preset deviation threshold and less than or equal to a third preset deviation threshold, the valve opening of the automatic throttling unit is controlled based on the parameter deviation, or the automatic grouting and pressurizing unit is controlled to reduce the output fluid flow rate;

[0075] If the parameter deviation is less than or equal to the fourth preset parameter deviation threshold, the valve opening of the automatic throttling unit and the fluid flow rate output by the automatic grouting and pressurizing unit are controlled to remain unchanged;

[0076] The automatic grouting booster unit is in the state of not replenishing fluid flow:

[0077] If the parameter deviation is greater than a fifth preset deviation threshold, controlling the valve opening of the automatic throttling unit to be a maximum value;

[0078] If the parameter deviation is greater than a sixth preset deviation threshold and less than or equal to a fifth preset deviation threshold, controlling the valve opening of the automatic throttling unit based on the parameter deviation;

[0079] If the parameter deviation is less than or equal to the sixth preset deviation threshold, the valve opening of the automatic throttling unit is kept unchanged.

[0080] In an optional embodiment, based on the parameter deviation between the target fluid parameter at the wellhead and the measured fluid parameter, the automatic grouting and pressurization unit is controlled to adjust the output fluid flow rate; including:

[0081] Based on the parameter deviation between the target fluid parameter at the wellhead and the measured fluid parameter, the required output fluid flow rate of the automatic grouting and pressurizing unit is obtained;

[0082] If the required output fluid flow rate is greater than the maximum output fluid flow rate of the automatic grouting and pressurizing unit, controlling the automatic grouting and pressurizing unit to perform fluid flow compensation at the maximum output fluid flow rate;

[0083] If the required output fluid flow rate is not greater than the maximum output fluid flow rate of the automatic grouting and pressurizing unit, the automatic grouting and pressurizing system is controlled to perform fluid flow compensation with the required output fluid flow rate.

[0084] In an optional embodiment, when the parameter deviation is greater than the second preset deviation threshold and less than or equal to the first preset deviation threshold, the parameter deviation is greater than the fourth preset deviation threshold and less than or equal to the third preset deviation threshold, and the parameter deviation is greater than the sixth preset deviation threshold and less than or equal to the fifth preset deviation threshold, the valve opening of the automatic throttling unit is controlled based on the parameter deviation; including:

[0085] Judging whether the system is stable based on the measured deviation between the measured fluid parameters at the current moment and the measured fluid parameters at the previous moment;

[0086] After the system is stable, the first stable parameter deviation after each adjustment is obtained based on the stabilized measured fluid parameters and the target fluid parameters at the wellhead;

[0087] Based on the first stable parameter deviation after the current adjustment and the first stable parameter deviation after the last adjustment, the opening of the throttle valve to be adjusted is determined in combination with a PID algorithm.

[0088] In an optional embodiment, if the parameter deviation is greater than the second preset deviation threshold and less than or equal to the first preset deviation threshold, and the parameter deviation is greater than the fourth preset deviation threshold and less than or equal to the third preset deviation threshold, the automatic grouting and boosting unit is controlled to adjust the output fluid flow based on the parameter deviation, including:

[0089] Judging whether the system is stable based on the measured deviation between the measured fluid parameters at the current moment and the measured fluid parameters at the previous moment;

[0090] After the system is stable, the second stable parameter deviation after each adjustment is obtained based on the stabilized measured fluid parameters and the target fluid parameters at the wellhead;

[0091] Based on the second stable parameter deviation after the current adjustment and the second stable parameter deviation after the last adjustment, the fluid flow rate to be compensated of the automatic grouting and pressurizing unit is determined in combination with the PID algorithm.

[0092] In an optional embodiment, when the fluid parameter is the fluid flow rate, obtaining the measured fluid parameter at the current moment includes:

[0093] The measured fluid flow at preset moments is retained and updated, a maximum value and a minimum value are removed, the average value is obtained for filtering, and the average value after filtering is used as the measured fluid flow at the current moment.

[0094] The beneficial effects of the above technical solution provided in the embodiments of the present invention include at least:

[0095] A pressure-controlled cementing system is provided in an embodiment of the present invention, comprising: an automatic throttling unit, an automatic grouting and pressurizing unit and a control center; wherein the automatic throttling unit is used to be arranged between a wellhead and a mud tank, the automatic grouting and pressurizing unit is used to be connected with a connecting pipeline between the wellhead and the automatic throttling unit, and the control center is used to control the automatic throttling unit to adjust the valve opening of the throttling valve to control the wellhead back pressure based on the deviation between the target fluid parameter of the wellhead and the corresponding measured fluid parameter, and / or control the automatic grouting and pressurizing unit to control the wellhead back pressure by adjusting the fluid flow rate compensated for the system; the automatic grouting and pressurizing unit in the pressure-controlled cementing provided in an embodiment of the present invention can adjust the output based on the deviation between the target fluid parameter of the wellhead and the measured fluid parameter. The fluid flow is used to control the wellhead back pressure, and the compensation range of the wellhead fluid flow is wider. For example, when the controlled wellhead back pressure value is large, the valve can be controlled to be at a preset opening, and the flow compensation is performed through the automatic grouting and boosting system to achieve the control of the wellhead back pressure, which can avoid the problem of low control accuracy caused by adjusting the valve opening of the throttle valve too small; that is, the system can better control the wellhead back pressure through the cooperation of the automatic grouting and boosting unit and the automatic throttling unit, reduce the leakage caused by high-density drilling fluid and cement slurry during cementing operations, ensure the stability of the wellbore pressure, improve the cementing quality, and provide technical support for effectively solving the problem of safe and efficient cementing of deep wells and ultra-deep wells under complex pressure conditions.

[0096] In the cementing system provided in the embodiment of the present invention, the throttle valve of the automatic throttling unit is an electric throttle valve, that is, the control mode of the automatic throttling unit is changed from the existing liquid-gas control mode to the gas-electric control mode. The control mode is simpler, and the control is faster and more convenient. It can avoid the high-pressure oil leakage in the high-pressure liquid circuit of the liquid-gas control mode during use, which affects the liquid-gas control efficiency and causes hidden dangers in the use of the equipment. In addition, the equipment required for the electrical control mode is more compact, which makes an important contribution to the miniaturization of the automatic throttling unit.

[0097] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description and the accompanying drawings.

[0098] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0099] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0100] Figure 1 It is a structural schematic diagram of a pressure-controlled cementing system provided in an embodiment of the present invention;

[0101] Figure 2 It is a structural schematic diagram of an automatic throttling skid provided in an embodiment of the present invention;

[0102] Figure 3 It is a schematic diagram of the structure of a modular straight-through skid provided in an embodiment of the present invention;

[0103] Figure 4 It is a structural schematic diagram of an automatic grouting and pressurizing unit provided in an embodiment of the present invention;

[0104] Figure 5 A schematic diagram of the structure of an entrance monitoring unit provided in an embodiment of the present invention;

[0105] Figure 6 A control logic diagram of an automatic throttling unit and an automatic grouting and pressurizing unit provided in an embodiment of the present invention;

[0106] Figure 7 The figure is a schematic flow chart of the pressure-controlled cementing method provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0107] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0108] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", "far", "near", "front", "back" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0109] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0110] In order to solve the problem that the pressure-controlled drilling equipment in the prior art cannot meet the requirements of pressure-controlled cementing operations in a complex formation pressure system environment, an embodiment of the present invention provides a pressure-controlled cementing system and method that overcomes the above problem or at least partially solves the above problem. It should be noted that the parameter deviation between the measured fluid parameters and the target fluid parameters at the wellhead mentioned in this embodiment specifically refers to the absolute value of the difference between the two.

[0111] The controlled pressure cementing system provided by the embodiment of the present invention refers to Figure 1 As shown, it includes: an automatic throttling unit 2000, an automatic grouting and pressurizing unit 4001 and a control center 5001;

[0112] The automatic throttling unit 2000 is used to be arranged between the wellhead and the mud tank 8 to control the wellhead back pressure by adjusting the valve opening of the throttling valve;

[0113] The automatic grouting and pressurizing unit 4001 is used to communicate with the connecting pipeline between the wellhead and the automatic throttling unit 2000 to control the wellhead back pressure by compensating the fluid flow of the system;

[0114] The control center 5001 is used to control the automatic throttling unit 2000 to adjust the valve opening of the throttling valve based on the target fluid parameter at the wellhead and the parameter deviation from the corresponding measured fluid parameter, and / or control the automatic grouting and pressurizing unit 4001 to adjust the output fluid flow rate to control the wellhead back pressure; wherein the fluid parameter includes: pressure or fluid flow rate, and correspondingly, the measured fluid parameter includes: the measured pressure of the throttling valve of the automatic throttling unit 2000 near the wellhead end or the measured fluid flow rate at the output end of the automatic throttling unit 2000. wherein, when the fluid parameter is the fluid flow rate, the target fluid flow rate at the wellhead is specifically the fluid flow rate corresponding to the target pressure at the wellhead.

[0115] Specifically, when the pressure-controlled cementing system of the embodiment of the present invention is used, the inlet of the automatic throttling unit 2000 is connected to the wellhead, and the outlet is connected to the mud tank 8, and the fluid returned from the wellhead or flowing out of the automatic grouting and pressurizing unit 4001 flows back to the mud tank 8 through the outlet of the automatic throttling unit 2000. When the automatic grouting and pressurizing unit 4001 is used to compensate the fluid flow of the system, the fluid source of the automatic grouting and pressurizing unit 4001 can be the mud tank 8 or a separately arranged fluid storage device, which is not specifically limited in the embodiment of the present invention.

[0116] When the fluid flow source of the automatic grouting and pressurizing unit is the mud tank 8, Figure 1 As shown, one end of the automatic grouting and pressurizing unit 4001 is used to communicate with the connecting pipeline between the wellhead and the automatic throttling unit 2000, and the other end is used to communicate with the mud tank 8; specifically, the inlet end of the automatic grouting and pressurizing unit is connected to the mud tank 8, and the outlet end thereof is connected to the connecting pipeline between the wellhead and the automatic throttling unit. The fluid in this embodiment can be specifically drilling fluid.

[0117] It should be noted that, since the fluid parameter in the embodiment of the present invention can be either pressure or fluid flow, the control center can control the automatic throttling unit to adjust the valve opening and control the operation of the automatic grouting and boosting unit according to the relevant pressure data, or according to the relevant fluid flow data. For example, it can be controlled according to the target fluid flow at the wellhead and the corresponding measured fluid flow, or it can be controlled according to the target pressure at the wellhead and the corresponding measured pressure. The embodiment of the present invention does not make specific limitations on this, and it can be selected according to actual needs.

[0118] In one embodiment, the control center 5001 is used to control the automatic throttling unit 2000 to adjust the valve opening of the throttling valve, and / or control the automatic grouting and pressurizing unit 4001 to adjust the output fluid flow rate based on the target fluid parameter at the wellhead and the parameter deviation of the corresponding measured fluid parameter; specifically including:

[0119] In the case where the measured fluid parameter is less than the target fluid parameter at the wellhead (i.e., in the case of chasing pressure), the control center 5001 is used to control the automatic throttling unit 2000 to adjust the valve opening of the throttling valve based on the target fluid parameter at the wellhead and the parameter deviation range of the corresponding measured fluid parameter, and / or control the automatic grouting and pressurizing unit 4001 to adjust the output fluid flow rate;

[0120] When the measured fluid parameters are greater than the target fluid parameters at the wellhead (i.e., under pressure reduction):

[0121] If the automatic grouting and pressurizing unit 4001 is in a state of supplementing fluid flow, the control center 5001 is used to control the automatic throttling unit 2000 to adjust the valve opening of the throttling valve based on the target fluid parameter at the wellhead and the parameter deviation range of the corresponding measured fluid parameter, and / or control the automatic grouting and pressurizing unit 4001 to adjust the output fluid flow;

[0122] If the automatic grouting and pressurizing unit 4001 is in a state of not replenishing fluid flow, the control center 5001 is used to control the automatic throttling unit 2000 to adjust the valve opening of the throttling valve based on the target fluid parameter at the wellhead and the parameter deviation range of the corresponding measured fluid parameter.

[0123] In one embodiment, when the measured fluid parameter is less than the target fluid parameter at the wellhead, the control center 5001 is used to control the automatic throttling unit 2000 to adjust the valve opening of the throttling valve and / or control the automatic grouting and pressurization unit 4001 to adjust the output fluid flow rate based on the target fluid parameter at the wellhead and the parameter deviation range of the corresponding measured fluid parameter; specifically including: when the measured fluid parameter is less than the target fluid parameter at the wellhead: the control center 5001 is used to,

[0124] When the parameter deviation between the target fluid parameter at the wellhead and the corresponding measured fluid parameter is greater than a first preset deviation threshold, the throttle valve of the automatic throttling unit 2000 is controlled to be at a preset opening, the measured fluid parameter when the valve is at the preset opening is obtained, and based on the parameter deviation between the measured fluid parameter and the target fluid parameter at the wellhead at this time, the automatic grouting and pressurization unit is controlled to increase the output fluid flow rate;

[0125] When the parameter deviation is greater than the second preset deviation threshold and less than or equal to the first preset deviation threshold, the valve opening of the throttle valve is controlled based on the parameter deviation, or the valve opening of the throttle valve is controlled to remain unchanged, and the automatic grouting and boosting unit 4001 is controlled to increase the output fluid flow rate based on the parameter deviation;

[0126] When the parameter deviation is less than or equal to the second preset parameter deviation, the valve opening of the automatic throttling unit and the fluid flow output by the automatic grouting and pressurizing unit are controlled to remain unchanged.

[0127] Among them, when the parameter deviation is greater than the first preset deviation threshold, the valve of the automatic throttling unit is controlled to be at a preset opening. The preset opening here can be the initial valve opening before the start of this control, or it can be the preset valve opening adjusted based on the control instruction of the control center 5001. The embodiment of the present invention does not make specific limitations on this.

[0128] In one embodiment, when the measured fluid parameter is greater than the target fluid parameter at the wellhead, if the automatic grouting and pressurizing unit 4001 is in a state of supplementing fluid flow, the control center 5001 is used to control the automatic throttling unit 2000 to adjust the valve opening of the throttling valve based on the target fluid parameter at the wellhead and the parameter deviation range of the corresponding measured fluid parameter, and / or control the automatic grouting and pressurizing unit 4001 to adjust the output fluid flow; if the automatic grouting and pressurizing unit 4001 is in a state of not supplementing fluid flow: the control center 5001 is used to control the automatic throttling unit 2000 to adjust the valve opening of the throttling valve based on the parameter deviation range; including:

[0129] When the measured fluid parameter is greater than the target fluid parameter at the wellhead: the automatic grouting and pressurizing unit 4001 is in the state of supplementing fluid flow:

[0130] The control center 5001 is used to control the automatic grouting and pressurizing unit 4001 to reduce the output fluid flow rate and control the valve opening of the automatic throttling unit 2000 to a maximum value based on the parameter deviation between the target fluid parameter at the wellhead and the corresponding measured fluid parameter when the parameter deviation between the target fluid parameter at the wellhead and the corresponding measured fluid parameter is greater than a third preset deviation threshold;

[0131] When the parameter deviation is greater than the fourth preset deviation threshold and less than or equal to the third preset deviation threshold, the valve opening of the automatic throttling unit 2000 is controlled based on the parameter deviation, or the automatic grouting and pressurizing unit 4001 is controlled to reduce the output fluid flow rate;

[0132] When the parameter deviation is less than or equal to the fourth preset parameter deviation threshold, the valve opening of the automatic throttling unit and the fluid flow output by the automatic grouting and pressurizing unit are controlled to remain unchanged.

[0133] It should be noted that the automatic grouting and pressurizing unit 4001 in this embodiment is in the state of supplementing fluid flow, including the following situations: (1) In the case of wellbore fluid circulation conditions such as circulation and injection, the drilling pump provides a large flow. If the flow of the drilling pump is limited and cannot meet the fluid circulation demand; at this time, the fluid flow can be output through the automatic grouting and pressurizing system, that is, the automatic grouting and pressurizing unit 4001 is in the state of supplementing fluid flow; (2) In the case of pump stop conditions such as drilling, valve inversion, and single connection, the automatic grouting and pressurizing unit 4001 provides drilling fluid circulation power and displacement to circulate the fluid on the ground, that is, the automatic grouting and pressurizing unit 4001 is in the state of supplementing fluid flow. In the above situation, if the measured fluid parameter is greater than the target fluid parameter at the wellhead, when the wellhead pressure is controlled, in addition to adjusting the valve opening of the throttle valve to control the wellhead pressure, the wellhead pressure can also be controlled by adjusting the fluid flow output by the automatic grouting and pressurizing unit 4001.

[0134] In one embodiment, when the measured fluid parameter is greater than the target fluid parameter at the wellhead, the automatic grouting and pressurizing unit 4001 is in a state where the fluid flow is not supplemented (for example, when the fluid flow provided by the drilling pump can meet the wellbore fluid circulation demand during wellbore fluid circulation conditions such as circulation and injection):

[0135] The control center is used to control the valve opening of the automatic throttling unit 2000 to be the maximum value when the parameter deviation is greater than the fifth preset deviation threshold;

[0136] When the parameter deviation is greater than the sixth preset deviation threshold and less than or equal to the fifth preset deviation threshold, the valve opening of the automatic throttling unit 2000 is controlled based on the parameter deviation;

[0137] When the parameter deviation is less than or equal to the sixth preset deviation threshold, the valve opening of the automatic throttling unit is controlled to remain unchanged.

[0138] In one embodiment, the embodiment of the present invention can also control the wellhead back pressure according to the high and low range of the wellhead back pressure and the wellbore fluid circulation displacement provided by the drilling pump, for example:

[0139] During normal drilling and circulation, due to the existence of annulus friction, the target wellhead back pressure value is generally low. For example, in the case of chasing pressure, when the parameter deviation is greater than the second preset deviation threshold and less than or equal to the first preset deviation threshold, and in the case of pressure reduction, when the parameter deviation is greater than the fifth preset deviation threshold and less than or equal to the sixth preset deviation threshold, it is preferred to control the wellhead back pressure by controlling the valve opening of the automatic throttling unit 2000 through the control center 5001, and the fluid parameter used to control the valve opening of the automatic throttling unit 2000 can be selected as pressure.

[0140] After stopping the pump or overflow control, when the bottom hole pressure needs to be restored, the target wellhead back pressure value is generally higher. For example, when the parameter deviation is greater than the first preset deviation threshold, the valve opening can be adjusted to the preset position by controlling the automatic throttling unit 2000, and the wellhead back pressure can be jointly controlled by the output flow of the automatic grouting and boosting unit 4001.

[0141] In the case of a large well section and a large wellbore size, and a large wellbore fluid circulation displacement provided by the drilling pump, the wellhead back pressure can generally be controlled by adjusting the valve opening of the automatic throttling unit, or by using the automatic grouting booster unit 4001 to compensate for a smaller fluid flow in the system;

[0142] In the lower well section, when the wellbore size is small and the wellbore fluid circulation displacement provided by the drilling pump is small, the automatic grouting and boosting unit 4001 can generally be used to compensate the system for a larger fluid flow to better control the wellhead back pressure.

[0143] It should be noted that the embodiments of the present invention do not specifically limit the specific sizes of the first preset deviation threshold, the second preset deviation threshold, the third preset deviation threshold, the fourth preset deviation threshold, the fifth preset deviation threshold, and the sixth preset deviation threshold, and can be selected according to actual needs; at the same time, the selection of each threshold also needs to be determined according to the specific fluid parameter. For example: when the fluid parameter is pressure, the first preset deviation threshold, the third preset deviation threshold, and the fifth preset deviation threshold can be 5MPa, and the second preset deviation threshold, the fourth preset deviation threshold, and the sixth preset deviation threshold can be set to 1MPa.

[0144] Further, the control center 5001 of this embodiment is used to control the automatic grouting and pressurizing unit 4001 to adjust the output fluid flow rate based on the parameter deviation between the measured fluid parameters and the target fluid parameters at the wellhead; specifically, the control center 5001 is used to obtain the output fluid flow rate required by the automatic grouting and pressurizing unit 4001 based on the parameter deviation between the measured fluid parameters and the target fluid parameters at the wellhead;

[0145] If the required output fluid flow rate is greater than the maximum output fluid flow rate of the automatic grouting and pressurizing unit 4001, the automatic grouting and pressurizing unit 4001 is controlled to perform fluid flow compensation at the maximum output fluid flow rate;

[0146] If the required output fluid flow is not greater than the maximum output fluid flow of the automatic grouting and pressurizing unit 4001, the automatic grouting and pressurizing system is controlled to perform fluid flow compensation with the required output fluid flow; that is, when the automatic grouting and pressurizing unit 4001 is used to perform flow compensation on the pressure controlled cementing system, the fluid flow to be compensated must be controlled to be no greater than the maximum fluid flow that can be output in its current state, so as to ensure the normal operation of the automatic grouting and pressurizing unit 4001.

[0147] Further, when the parameter deviation is greater than the second preset deviation threshold and less than or equal to the first preset deviation threshold, the parameter deviation is greater than the fourth preset deviation threshold and less than or equal to the third preset deviation threshold, and the parameter deviation is greater than the sixth preset deviation threshold and less than or equal to the fifth preset deviation threshold, the valve opening of the automatic throttling unit 2000 is controlled based on the parameter deviation; including:

[0148] Judging whether the system is stable based on the measured deviation between the measured fluid parameters at the current moment and the measured fluid parameters at the previous moment;

[0149] After the system is stable, the first stable parameter deviation after each adjustment is obtained based on the stabilized measured fluid parameters and the target fluid parameters at the wellhead;

[0150] Based on the first stable parameter deviation after the current adjustment and the first stable parameter deviation after the last adjustment, the opening of the throttle valve to be adjusted is determined in combination with the PID algorithm.

[0151] If the parameter deviation is greater than the fourth preset deviation threshold and less than or equal to the third preset deviation threshold, and if the parameter deviation is greater than the fourth preset deviation threshold and less than or equal to the third preset deviation threshold, the automatic grouting and boosting unit is controlled to adjust the output fluid flow based on the parameter deviation, including:

[0152] Judging whether the system is stable based on the measured deviation between the measured fluid parameters at the current moment and the measured fluid parameters at the previous moment;

[0153] After the system is stable, the second stable parameter deviation after each adjustment is obtained based on the stabilized measured fluid parameters and the target fluid parameters at the wellhead;

[0154] Based on the second stable parameter deviation after the current adjustment and the second stable parameter deviation after the last adjustment, the fluid flow rate to be compensated of the automatic grouting and boosting unit is determined in combination with the PID algorithm.

[0155] Specifically, when the control center 5001 of this embodiment calculates the adjustment amount based on the PID algorithm, its specific calculation formula is as follows:

[0156] ΔU(k)=u(k)-u(k-1)=k p (e(k)-e(k-1))+k i e(k)

[0157] In the formula, k p is the proportionality coefficient; k i is the integral coefficient; e(k)-e(k-1) is the current adjusted stability parameter deviation - the last adjusted stability parameter deviation; e(k) is the current adjusted stability parameter deviation; where the proportional coefficient k p and the integration coefficient ki The specific value of can be obtained through experimental tests, and specific reference can be made to the prior art, which will not be elaborated in detail in this embodiment.

[0158] In one embodiment, taking the initial state of the automatic grouting and pressurizing unit 4001 as a state where the fluid flow is not replenished, the fluid parameter is pressure, the first preset deviation threshold and the fifth preset deviation threshold can be 5MPa, and the second preset deviation threshold and the sixth preset deviation threshold can be set to 1MPa as an example, the specific control process of the pressure chasing stage and the pressure reduction stage is exemplarily described as follows:

[0159] In the pressure chasing stage, if the pressure difference between the target pressure at the wellhead and the measured pressure is greater than the first preset deviation threshold of 5MPa, the valve opening of the throttle valve of the automatic throttling unit 2000 is controlled to remain unchanged, and the fluid flow output by the automatic grouting and boosting unit 4001 is set to the maximum flow allowed under the maximum power corresponding to the current measured pressure value to ensure the fastest speed of pressure chasing; if the pressure difference is between the first preset deviation threshold of 5MPa and the second preset deviation threshold of 1MPa, then referring to the idea of ​​incremental PID, the difference and the difference increment are used to adopt proportional action and integral action to feedback and adjust the fluid flow output by the automatic grouting and boosting unit 4001 or the valve opening of the throttle valve of the automatic throttling unit 2000;

[0160] In the pressure reduction mode, if the pressure difference is greater than the fifth preset deviation threshold value, such as 5MPa, the valve opening of the throttle valve of the automatic throttling unit 2000 will be controlled to the maximum value to ensure the fastest pressure reduction; if the pressure difference is between the fifth preset deviation threshold value 5MPa and the sixth preset deviation threshold value 1MPa, then referring to the idea of ​​incremental PID, the difference and the difference increment are used to adopt proportional and integral actions to feedback adjust the valve opening of the throttle valve of the automatic throttling unit 2000.

[0161] In one embodiment, the automatic grouting and pressurizing unit 4001, the structural schematic diagram of which is shown in FIG. Figure 4 As shown, it includes: a hydraulic component 4003, an electrical control component 4002 and a piston pump 4005;

[0162] The electrical control component is electrically connected to the control center 5001 to receive control instructions from the control center 5001, and based on the control instructions, controls the hydraulic component 4003 to drive the piston pump 4005 to output fluid flow; when the fluid flow source of the automatic grouting and boosting unit is the mud tank 8, the piston pump 4005 is connected to the mud tank 8.

[0163] The automatic grouting and boosting unit 4001 of the present embodiment adopts a hydraulically controlled piston pump instead of traditional motor control, and adjusts the flow of the hydraulic component to adjust the measured fluid flow of the piston pump, and can realize variable frequency control, with a large adjustment range and higher adjustment accuracy. The flow adjustment accuracy of the automatic grouting and boosting unit 4001 in the present embodiment can reach 0.5L / s.

[0164] Among them, in this embodiment, the piston pump of the automatic grouting and boosting unit 4001 can be specifically a hydraulically driven piston pump, and the reliability and stability of the hydraulically driven piston pump are better than those of an ordinary drilling pump; and because the drilling fluid is relatively alkaline and has a certain content of solid particles, in actual application, the cylinder liner of the pump used and the places where the drilling fluid medium passes must undergo anti-corrosion and wear-resistant treatments.

[0165] Furthermore, the automatic grouting and boosting unit 4001 also includes a dynamic monitoring module (not shown in the figure) to monitor the outlet pressure, outlet flow, temperature, voltage, and current data of the automatic grouting and boosting unit 4001 in real time, and to issue an early warning reminder when the monitoring data is abnormal. The operator can judge whether the automatic grouting and boosting unit 4001 is in a healthy and normal working state based on the early warning reminder (for example: when the outlet pressure is abnormal, it may be due to blockage in the automatic grouting and boosting unit 4001, such as the piston pump), so as to improve the safety of the automatic grouting and boosting unit 4001. Among them, the voltage and current specifically refer to the voltage and current of the electrical control component, and the temperature specifically refers to the temperature of the hydraulic oil in the hydraulic component. It should be noted that the dynamic monitoring unit can issue different early warning signals to indicate that different monitoring data are abnormal, wherein the early warning signal can be an optical signal or an acoustic signal, and the embodiment of the present invention does not specifically limit this.

[0166] Furthermore, the automatic grouting and pressurizing unit 4001 may further include: a first human-machine interaction (HMI) module (not shown in the figure);

[0167] The first human-machine interaction module is used to control the automatic grouting and pressurizing unit 4001 based on the operator's operating instructions, record and analyze the real-time monitoring data, and issue an alarm and perform fault diagnosis when the real-time monitoring data is abnormal;

[0168] Correspondingly, the electrical control component is also used to control the hydraulic component to drive the piston pump to work and output fluid flow based on the control instruction of the first human-machine interaction module.

[0169] In one embodiment, referring to Figure 1 As shown, the automatic throttling unit 2000 includes: a modular straight-through skid 2001 and an automatic throttling skid assembly 3000, and the automatic throttling skid assembly 3000 includes at least one modular automatic throttling skid (3001, 3002);

[0170] The modular straight-through skid 2001 is arranged in parallel with the automatic throttling skid assembly 3000;

[0171] Furthermore, when the automatic throttling skid assembly 3000 includes two or more automatic throttling skids (3001, 3002), the automatic throttling skids are arranged in parallel.

[0172] That is, the automatic throttling unit 2000 of the embodiment of the present invention can be divided into two working modes, throttling mode and direct current mode, according to whether throttling is applied to the wellhead back pressure, and the automatic throttling skid assembly can be used in combination with one or more automatic throttling skids to perform single throttling channel or multiple throttling channels in parallel. In actual application, a single automatic throttling skid is generally used in conjunction with a direct current channel skid. For complex formations with narrow density windows, multiple automatic throttling skids can be used in combination. On the one hand, there are spare automatic throttling channels to switch the automatic throttling channels when necessary; on the other hand, if the flow rate is large, the automatic throttling channels can be used in parallel. This embodiment does not specifically limit the number of automatic throttling skids included in the automatic throttling skid assembly, and can be selected according to actual needs.

[0173] In one embodiment, referring to Figure 2 As shown, the modular automatic throttling skid comprises: an electric control cabinet and an electric throttling valve 33 arranged on the throttling pipeline;

[0174] The electric control cabinet is used to control the valve opening of the electric throttle valve 33 based on the control instruction of the control center 5001.

[0175] Further, see Figure 2 As shown, the modular automatic throttling skid further includes: an air control cabinet, a first pressure sensor 31, an air control flat valve 32, a first needle valve 34, a manual valve 35, a second pressure sensor 36, a filter 37, a second needle valve 38 and a mass flow meter 39 which are sequentially arranged on the throttling pipeline;

[0176] The gas control cabinet is used to control the opening and closing of the gas-controlled flat valve based on the control instructions of the control center 5001;

[0177] The electric throttle valve 33 is arranged between the air-controlled flat valve 32 and the first needle valve 34, wherein the pressure detected by the first pressure sensor 31 is used as the measured pressure, and the fluid flow detected by the mass flow meter 39 is used as the measured fluid flow, and the mass flow meter 39 can also be used to detect the fluid density, wherein the detected fluid density can be used to calculate the wellhead target pressure; the pressure difference between the second pressure sensor 36 and the first pressure sensor 31 is the pressure difference controlled by the automatic throttling unit; the manual valve 35 can specifically be a manual plug valve or a manual flat valve, and specifically, in actual applications, the automatic throttling unit and the automatic grouting and boosting unit can be connected through the air-controlled flat valve 32.

[0178] The throttle valve of the automatic throttling unit 2000 in the embodiment of the present invention is specifically an electric throttle valve, that is, the control method of the automatic throttling unit 2000 is changed from the existing liquid-gas control method to the gas-electric control method. The control method is simpler, the control is faster and more convenient, the stability is good, the control accuracy is high, and the high-pressure oil leakage of the high-pressure liquid circuit of the liquid-gas control method can be avoided during use, which affects the liquid-gas control efficiency and causes hidden dangers in the use of the equipment. The equipment required for the electrical control method is more compact, which makes an important contribution to the miniaturization of the automatic throttling unit 2000.

[0179] In one embodiment, referring to Figure 3 As shown, the modular straight-through skid includes: a main pipeline 201 and a first pipeline 202 and a second pipeline 203 connected to the main pipeline 201, the first pipeline 202 and the second pipeline 203 are respectively used to communicate with the inlet and outlet of the throttling pipeline of the modular automatic throttling skid, and the main pipeline 201, the first pipeline 202 and the second pipeline 203 are respectively provided with flat valves (21, 22, 23) for controlling the on-off of the pipeline; wherein, the flat valves for controlling the on-off of the main pipeline 201, the first pipeline 202 and the second pipeline 203 can be manual flat valves or pneumatic flat valves, and the embodiment of the present invention does not specifically limit the type thereof, and can be selected according to actual needs.

[0180] During actual application, in the throttling mode of the automatic throttling unit 2000, the pneumatically controlled flat valve 32, the electric throttling valve 33, and the manual valve 35 of the automatic throttling skid are in the open state, and the flat valve of the modular straight-through skid is closed; in direct current mode: the flat valve of the modular straight-through skid is open, and the pneumatically controlled flat valve of the automatic throttling skid is closed.

[0181] In one embodiment, the modular straight-through skid and automatic throttling skid can be a one-skid-one-system structure, that is, various functional components are integrated on an integral base and can be installed and moved as a whole, so that different modules can be quickly installed and configured according to on-site requirements during subsequent use.

[0182] In one embodiment, the automatic throttling unit 2000 may further include: a second human-machine interaction (HMI) module (not shown in the figure);

[0183] The second human-computer interaction module is used to control the automatic throttling unit 2000 based on the operator's operating instructions, record and analyze the real-time monitoring data, and issue alarms and fault diagnosis when the real-time monitoring data is abnormal; wherein the real-time detection data may include: the pressure and fluid flow of the automatic throttling unit 2000.

[0184] Correspondingly, the gas control cabinet is also used to control the opening and closing of the gas-controlled flat valve based on the control instructions of the second human-machine interaction module;

[0185] The electric control cabinet is also used to control the valve opening of the electric throttle valve based on the control instruction of the second human-machine interaction module.

[0186] That is, in addition to being remotely monitored and controlled through the control center 5001, the automatic throttling unit 2000 of this embodiment can also be locally controlled through the human-computer interaction module according to the actual situation of the well site; further, the automatic throttling unit 2000 can realize the opening or closing of the gas-controlled flat valve under different working conditions such as pressure control cycle, pressure control connection of columns / single roots, pressure control drilling, pressure control drilling, pressure control injection of cement slurry, pressure control center pipe extraction, pressure control waiting for solidification, pressure control replacement of rubber core, pressure control of mud cap installation, pressure control well leakage operation, pressure control density reduction operation, and sequential logic control of the valve opening adjustment of the electric throttle valve through the control algorithm of the control center 5001 or the human-computer interaction mode.

[0187] In one embodiment, the control mode of the automatic throttling unit 2000, the automatic grouting and pressurizing unit 4001 and other units in the embodiment of the present invention includes two operation modes: remote mode and local mode. Figure 6 Specifically, in this embodiment, remote control specifically refers to control by the control center 5001, wherein the remote mode is further divided into a remote automatic mode and a remote manual mode. The remote manual mode can be to manually adjust the valve opening or the fluid flow output by the automatic grouting and boosting unit 4001 through the screen at the control center 5001, and the remote automatic mode can be to automatically adjust the throttle valve opening or the fluid flow output by the automatic grouting and boosting unit 4001 through the algorithm according to the automatic given target or set target through the automatic mode button at the control center 5001.

[0188] Among them, the local mode can be divided into a local handle control mode and a local touch control mode. In the local handle control mode, the automatic throttling unit 2000 and the automatic grouting and boosting unit 4001 can control the opening and closing of the air-controlled flat valve and adjust the valve opening of the electric throttle valve by manually opening or closing the switch button of the operating cabinet (for example: the air control cabinet or the electric control cabinet); in the touch control mode, the corresponding control modules (such as the second human-computer interaction module of the automatic throttling unit 2000 and the first human-computer interaction module of the automatic grouting and boosting unit 4001) can be set through each unit to manually adjust the valve opening of the electric throttle valve, control the opening and closing of the air-controlled flat valve or adjust the fluid flow output by the automatic grouting and boosting unit 4001.

[0189] It should be noted that, in actual applications, the embodiments of the present invention do not specifically limit the control modes of the automatic throttling unit 2000 and the automatic grouting and pressurizing unit 4001, and they can be selected according to actual needs; among them, the control center 5001 of the embodiments of the present invention can specifically be an automated control system such as a programmable logic controller (PLC) or DeltaV (digital automation system).

[0190] The control center 5001 is also used to provide a safety protection mode and / or an expert mode;

[0191] The safety protection mode is used to give an early warning when the measured pressure is abnormal, and to perform one or more of the following controls:

[0192] Control the electric throttle valve opening of the currently used automatic throttle skid to the maximum;

[0193] When the flat valve of the modular direct-flow skid is a pneumatically controlled flat valve, the pneumatic flat valve of the modular direct-flow skid is controlled to open;

[0194] When multiple automatic throttling skids are provided, the gas-controlled flat valves of other automatic throttling skids are controlled to open.

[0195] That is, in the safety protection mode, when the measured pressure is abnormal, the control center can not only control the electric throttle valve of the automatic throttling skid currently in use to open to the maximum, but also open other channels such as the DC channel to avoid high pressure caused by abnormal drilling, such as the presence of large particles of rock cuttings in the currently used throttling channel, which blocks the channel.

[0196] At the same time, technical personnel in related fields can also perform relevant operations based on the early warning reminder. For example, when the flat valve of the modular straight-through skid is a manual flat valve, the operator manually opens the manual flat valve of the modular straight-through skid based on the early warning reminder.

[0197] The expert mode is used to enable the operation authority based on the authority instruction input by the operator, and after the operation authority is enabled, perform related operations based on the control instruction input by the operator, and the related operations include: conventional operations in non-expert mode and designated operations in expert mode; designated operations include: closing the electric control throttle valve, and / or the gas control flat valve. Specifically, in the expert mode, in addition to controlling all operations in the non-expert mode, some designated controls that can only be performed when the operation authority of the expert mode is enabled can also be performed, so as to avoid affecting the overall construction operation due to misoperation by other staff under normal construction conditions, thereby improving the safety of cementing operations.

[0198] In one embodiment, the pressure controlled cementing system of the present invention refers to Figure 1 As shown, it may also include: an entrance monitoring unit;

[0199] The inlet monitoring unit is used to be connected to the wellhead entry pipe string to monitor the pressure and flow of the fluid entering the wellbore in real time. The fluid entering the wellbore can be drilling fluid or cement slurry.

[0200] Further, see Figure 1 As shown, during cementing operation, the controlled pressure cementing system further includes: a cementing pump 2 and a drilling pump 1;

[0201] The drilling pump 1 and the cementing pump 2 are respectively connected to the wellhead entry pipe string;

[0202] Reference Figure 5 As shown, the inlet measurement unit includes: a first measurement pipeline 101 and a first flow meter 11 and a third pressure sensor 12 arranged thereon, a second measurement pipeline 102 and a second flow meter 13 and a fourth pressure sensor 14 arranged thereon;

[0203] The first measuring pipeline 101 is used to connect with the connecting pipeline between the cementing pump 2 and the wellhead entering pipe string; the second measuring pipeline 102 is used to connect with the connecting pipeline between the drilling pump 1 and the wellhead entering pipe string.

[0204] Among them, the first flowmeter and the second flowmeter can be specifically turbine flowmeters, and the first measuring pipeline and the second measuring pipeline can be specifically casing short sections; that is, considering the inlet end space, pressure, fluid conditions and limiting factors, the inlet monitoring unit is arranged in the form of a "flowmeter + pressure sensor" short section. The size of the short section pipe body can be consistent with the size of the cementing site manifold, and it can be quickly connected to the wellhead pipe body using a union method, and the pressure level can meet the pressure test requirements of the cementing manifold, ensuring that the entire short section can be placed on the drilling floor to measure the drilling fluid inlet parameters, so that it can be combined with the outlet pressure gauge flow parameters of the wellhead later to more accurately analyze the drilling fluid circulation status downhole.

[0205] Further, see Figure 1 As shown, the pressure controlled cementing system may also include: a rotating control head 3 arranged at the wellhead, a well team throttling manifold 10, a manual valve 9, and a vibrating screen 7 arranged between the automatic throttling unit and the mud tank, etc. Its specific structure and setting position are consistent with those in the prior art, and specific reference may be made to the prior art. The embodiment of the present invention does not make specific limitations on this.

[0206] Based on the same inventive concept, the embodiment of the present invention also provides a pressure controlled cementing method, the flow chart of which is shown in FIG. Figure 7 As shown, the following steps are included:

[0207] Step S101: Acquire target fluid parameters at the wellhead and corresponding measured fluid parameters; the fluid parameters include: pressure and / or fluid flow rate, and correspondingly, the measured fluid parameters include: the measured pressure at one end of the throttle valve of the automatic throttling unit close to the wellhead, and / or the fluid flow rate at the output end of the automatic throttling unit;

[0208] Step S102: Based on the parameter deviation between the target fluid parameter at the wellhead and the corresponding measured fluid parameter, the automatic throttling unit is controlled to adjust the valve opening, and / or the automatic grouting and pressurizing unit is controlled to adjust the output fluid flow rate to control the wellhead back pressure.

[0209] Further: in step S102, based on the parameter deviation between the target fluid parameter at the wellhead and the corresponding measured fluid parameter, the automatic throttling unit is controlled to adjust the opening of the valve, and / or the automatic grouting and pressurizing unit is controlled to adjust the output fluid flow, specifically including:

[0210] In the case where the measured fluid parameter is less than the target fluid parameter at the wellhead, based on the target fluid parameter at the wellhead and the parameter deviation range of the corresponding measured fluid parameter, the automatic throttling unit is controlled to adjust the valve opening of the throttling valve, and / or the automatic grouting and pressurizing unit is controlled to adjust the output fluid flow rate;

[0211] In the case where the measured fluid parameter is greater than the target fluid parameter at the wellhead, if the automatic grouting and pressurization unit is in a state of supplementing the fluid flow, the automatic throttling unit is controlled to adjust the valve opening of the throttling valve and / or the automatic grouting and pressurization unit is controlled to adjust the output fluid flow based on the target fluid parameter at the wellhead and the parameter deviation range of the corresponding measured fluid parameter; if the automatic grouting and pressurization unit is in a state of not supplementing the fluid flow, the automatic throttling unit is controlled to adjust the valve opening of the throttling valve based on the parameter deviation range.

[0212] Further, in the case where the measured fluid parameter is less than the target fluid parameter at the wellhead, based on the target fluid parameter at the wellhead and the parameter deviation range of the corresponding measured fluid parameter, the automatic throttling unit is controlled to adjust the valve opening of the throttling valve, and / or the automatic grouting and pressurizing unit is controlled to adjust the output fluid flow rate, specifically including: in the case where the measured fluid parameter is less than the target fluid parameter at the wellhead:

[0213] If the parameter deviation between the target fluid parameter at the wellhead and the corresponding measured fluid parameter is greater than a first preset deviation threshold, the throttle valve of the automatic throttling unit is controlled to be at a preset opening, the measured fluid parameter when the valve is at the preset opening is obtained, and based on the parameter deviation between the measured fluid parameter and the target fluid parameter at the wellhead, the automatic grouting and pressurizing unit is controlled to increase the output fluid flow rate;

[0214] If the parameter deviation is greater than a second preset deviation threshold and less than or equal to the first preset deviation threshold, the opening of the throttle valve is controlled based on the parameter deviation to control the wellhead back pressure, or the opening of the throttle valve is controlled to remain unchanged, and the automatic grouting and boosting unit is controlled based on the parameter deviation to increase the output fluid flow rate;

[0215] If the parameter deviation is less than or equal to the second preset parameter deviation, the valve opening of the automatic throttling unit and the fluid flow output by the automatic grouting and pressurizing unit are kept unchanged.

[0216] In one embodiment, when the measured fluid parameter is greater than the target fluid parameter at the wellhead, if the automatic grouting and pressurizing unit is in a state of supplementing fluid flow, based on the target fluid parameter at the wellhead and the parameter deviation range of the corresponding measured fluid parameter, the automatic throttling unit is controlled to adjust the valve opening of the throttling valve, and / or the automatic grouting and pressurizing unit is controlled to work; if the automatic grouting and pressurizing unit is in a state of not supplementing fluid flow: the automatic throttling unit is controlled to adjust the valve opening of the throttling valve; specifically including: when the measured fluid parameter is greater than the target fluid parameter at the wellhead:

[0217] The automatic grouting and boosting unit is in the state of supplementing fluid flow:

[0218] If the parameter deviation between the target fluid parameter at the wellhead and the corresponding measured fluid parameter is greater than a third preset deviation threshold, based on the parameter deviation, the automatic grouting and pressurizing unit is controlled to reduce the output fluid flow rate, and the valve opening of the automatic throttling unit is controlled to be the maximum value;

[0219] If the parameter deviation is greater than the fourth preset deviation threshold and less than or equal to the third preset deviation threshold, the valve opening of the automatic throttling unit is controlled based on the parameter deviation, or the automatic grouting and boosting unit is controlled to reduce the output fluid flow rate;

[0220] If the parameter deviation is less than or equal to the fourth preset parameter deviation, the valve opening of the automatic throttling unit and the fluid flow output by the automatic grouting and boosting unit are kept unchanged;

[0221] The automatic grouting booster unit is in the state of not replenishing fluid flow:

[0222] If the parameter deviation is greater than a fifth preset deviation threshold, controlling the valve opening of the automatic throttling unit to be a maximum value;

[0223] If the parameter deviation is greater than a sixth preset deviation threshold and less than or equal to a fifth preset deviation threshold, controlling the valve opening of the automatic throttling unit based on the parameter deviation;

[0224] If the parameter deviation is less than or equal to the sixth preset deviation threshold, the valve opening of the automatic throttling unit is kept unchanged.

[0225] Further, based on the parameter deviation between the target fluid parameter at the wellhead and the measured fluid parameter, the automatic grouting and pressurizing unit is controlled to adjust the output fluid flow rate; including:

[0226] Based on the parameter deviation between the target fluid parameter at the wellhead and the measured fluid parameter, the required output fluid flow rate of the automatic grouting and pressurizing unit is obtained;

[0227] If the required output fluid flow rate is greater than the maximum output fluid flow rate of the automatic grouting and pressurizing unit, the automatic grouting and pressurizing unit is controlled to perform fluid flow compensation at the maximum output fluid flow rate;

[0228] If the required output fluid flow is not greater than the maximum output fluid flow of the automatic grouting and pressurizing unit, the automatic grouting and pressurizing system is controlled to perform fluid flow compensation with the required output fluid flow.

[0229] In one embodiment, when the parameter deviation is greater than the second preset deviation threshold and less than or equal to the first preset deviation threshold, the parameter deviation is greater than the fourth preset deviation threshold and less than or equal to the third preset deviation threshold, and the parameter deviation is greater than the sixth preset deviation threshold and less than or equal to the fifth preset deviation threshold, the valve opening of the automatic throttling unit is controlled based on the parameter deviation; comprising:

[0230] Judging whether the system is stable based on the measured deviation between the measured fluid parameters at the current moment and the measured fluid parameters at the previous moment;

[0231] After the system is stable, the first stable parameter deviation after each adjustment is obtained based on the stabilized measured fluid parameters and the target fluid parameters at the wellhead;

[0232] Based on the first stable parameter deviation after the current adjustment and the first stable parameter deviation after the last adjustment, the opening of the throttle valve to be adjusted is determined in combination with the PID algorithm.

[0233] In one embodiment, if the parameter deviation is greater than the second preset deviation threshold and less than or equal to the first preset deviation threshold, and the parameter deviation is greater than the fourth preset deviation threshold and less than or equal to the third preset deviation threshold, adjusting the fluid flow rate of the automatic grouting and boosting unit to compensate the system based on the parameter deviation includes:

[0234] Judging whether the system is stable based on the measured deviation between the measured fluid parameters at the current moment and the measured fluid parameters at the previous moment;

[0235] After the system is stable, the second stable parameter deviation after each adjustment is obtained based on the stabilized measured fluid parameters and the target fluid parameters at the wellhead;

[0236] Based on the second stable parameter deviation after the current adjustment and the second stable parameter deviation after the last adjustment, the fluid flow rate to be compensated of the automatic grouting and boosting unit is determined in combination with the PID algorithm.

[0237] In one embodiment, when the fluid parameter is the fluid flow rate, obtaining the measured fluid parameter at the current moment includes:

[0238] The measured fluid flow at the preset moments is retained and updated, a maximum value and a minimum value are removed, an average value is obtained for filtering, and the average value after filtering is used as the measured fluid flow at the current moment. Among the measured fluids at the preset moments retained, the specific number of the preset moments can be selected according to actual needs, and the embodiment of the present invention does not limit it. For example, the preset moments can be specifically 10 moments.

[0239] It should be noted that the specific process of the controlled pressure cementing method provided in the embodiment of the present invention has been described in detail in the relevant content of the above-mentioned controlled pressure cementing system, which can be referred to for details and will not be elaborated in detail in this embodiment.

[0240] The pressure-controlled cementing method and system provided in the embodiment of the present invention are designed to meet the requirements of higher wellhead pressure, faster pressure regulation speed, better pressure regulation adaptability, inlet pressure flow measurement during cementing, etc. for the regulation and control of wellhead pressure due to the complex process of pressure-controlled cementing. The pressure-controlled cementing system of this embodiment is designed. The system includes: an automatic throttling unit capable of adaptively adjusting wellhead back pressure, an automatic grouting and pressurizing unit capable of compensating outlet flow and improving wellhead back pressure, an inlet monitoring unit capable of monitoring inlet pressure and flow, and a control center for accurately controlling the automatic grouting and pressurizing unit and the automatic throttling unit, so as to perform adaptive dynamic monitoring and adjustment of pressure and flow during the whole cementing process, realize efficient and automated pressure control, effectively reduce leakage caused by high-density drilling fluid and cement slurry, ensure stable wellbore pressure, improve cementing quality, and provide technical support for effectively solving the problem of safe and efficient cementing of deep wells and ultra-deep wells under complex pressure conditions.

[0241] In combination with the pressure-controlled cementing system and method of the embodiments of the present invention, when displacing cement slurry during pressure-controlled cementing operations, a larger displacement can be used, the reliability of the cementing operation process is higher, and the casing can be lowered deeper; and when performing cementing operations, the ratio of the casing outer diameter to the wellbore inner diameter can better meet the requirements of the cementing operation, that is, the requirements for the ratio of the casing outer diameter to the wellbore inner diameter are reduced.

[0242] Obviously, various changes and modifications may be made to the present invention by those skilled in the art without departing from the spirit and scope of the present invention. The present disclosure is not limited to the precise structure described above and shown in the accompanying drawings, and various changes and modifications may be made without departing from the scope thereof. The scope of the present disclosure is limited only by the appended claims. Thus, if these changes and modifications of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these changes and modifications.

Claims

1. A pressure controlled cementing system, characterized in that: include: Automatic throttling unit, automatic grouting and pressurizing unit and control center; The automatic throttling unit is used to be arranged between the wellhead and the mud tank to control the wellhead back pressure by adjusting the valve opening of the throttling valve; The automatic grouting and pressurizing unit is used to communicate with the connecting pipeline between the wellhead and the automatic throttling unit to control the wellhead back pressure by compensating the system fluid flow; The control center is used to control the automatic throttling unit to adjust the valve opening of the throttling valve based on the target fluid parameter at the wellhead and the parameter deviation of the corresponding measured fluid parameter, and / or control the automatic grouting and pressurizing unit to adjust the output fluid flow rate to control the wellhead back pressure; The fluid parameters include: pressure or fluid flow, and correspondingly, the measured fluid parameters include: the measured pressure at one end of the throttle valve of the automatic throttling unit close to the wellhead or the measured fluid flow at the output end of the automatic throttling unit.

2. The pressure controlled cementing system according to claim 1, characterized in that: The control center is used to control the automatic throttling unit to adjust the valve opening of the throttling valve, and / or control the automatic grouting and pressurizing unit to adjust the output fluid flow rate based on the parameter deviation between the target fluid parameter at the wellhead and the corresponding measured fluid parameter; include: When the measured fluid parameter is less than the target fluid parameter of the wellhead: the control center is used to control the automatic throttling unit to adjust the valve opening of the throttling valve, and / or control the automatic grouting and boosting unit to adjust the output fluid flow rate based on the target fluid parameter of the wellhead and the parameter deviation range of the corresponding measured fluid parameter; When the measured fluid parameter is greater than the target fluid parameter of the wellhead: If the automatic grouting and pressurizing unit is in a state of supplementing fluid flow, the control center is used to control the automatic throttling unit to adjust the valve opening of the throttling valve and / or control the automatic grouting and pressurizing unit to adjust the output fluid flow based on the target fluid parameter of the wellhead and the parameter deviation range of the corresponding measured fluid parameter; If the automatic grouting and pressurizing unit is in a state of not replenishing fluid flow, the control center is used to control the automatic throttling unit to adjust the valve opening of the throttling valve based on the target fluid parameter of the wellhead and the parameter deviation range of the corresponding measured fluid parameter.

3. The pressure controlled cementing system according to claim 2, characterized in that: When the measured fluid parameter is less than the target fluid parameter at the wellhead: the control center is used to control the automatic throttling unit to adjust the valve opening of the throttling valve and / or control the automatic grouting and pressurization unit to adjust the output fluid flow rate based on the target fluid parameter at the wellhead and the parameter deviation range of the corresponding measured fluid parameter; including: when the measured fluid parameter is less than the target fluid parameter at the wellhead: the control center is used to, When the parameter deviation between the target fluid parameter at the wellhead and the corresponding measured fluid parameter is greater than a first preset deviation threshold, the throttle valve of the automatic throttling unit is controlled to be at a preset opening, the measured fluid parameter when the valve is at the preset opening is obtained, and based on the parameter deviation between the measured fluid parameter and the target fluid parameter at the wellhead at this time, the automatic grouting and pressurization unit is controlled to increase the output fluid flow rate; When the parameter deviation is greater than a second preset deviation threshold and less than or equal to a first preset deviation threshold, the valve opening of the throttle valve is controlled based on the parameter deviation, or the valve opening of the throttle valve is controlled to remain unchanged, and the automatic grouting and boosting unit is controlled based on the parameter deviation to increase the output fluid flow rate; When the parameter deviation is less than or equal to the second preset parameter deviation, the valve opening of the automatic throttling unit and the fluid flow output by the automatic grouting and pressurizing unit are controlled to remain unchanged.

4. The pressure controlled cementing system according to claim 2, characterized in that: In the case where the measured fluid parameter is greater than the target fluid parameter of the wellhead, if the automatic grouting and pressurizing unit is in a state of supplementing fluid flow, the control center is used to control the automatic throttling unit to adjust the valve opening of the throttling valve based on the target fluid parameter of the wellhead and the parameter deviation range of the corresponding measured fluid parameter, and / or control the automatic grouting and pressurizing unit to adjust the output fluid flow; if the automatic grouting and pressurizing unit is in a state of not supplementing fluid flow: the control center is used to control the automatic throttling unit to adjust the valve opening of the throttling valve based on the parameter deviation range; including: When the measured fluid parameter is greater than the target fluid parameter of the wellhead: The automatic grouting and boosting unit is in the state of supplementing fluid flow: The control center is used to control the automatic grouting and pressurizing unit to reduce the output fluid flow rate and control the valve opening of the automatic throttling unit to a maximum value based on the parameter deviation between the target fluid parameter at the wellhead and the corresponding measured fluid parameter when the parameter deviation between the target fluid parameter at the wellhead and the corresponding measured fluid parameter is greater than a third preset deviation threshold; When the parameter deviation is greater than a fourth preset deviation threshold and less than or equal to a third preset deviation threshold, controlling the valve opening of the automatic throttling unit based on the parameter deviation, or controlling the automatic grouting and pressurizing unit to reduce the output fluid flow; When the parameter deviation is less than or equal to the fourth preset parameter deviation threshold, the valve opening of the automatic throttling unit and the fluid flow rate output by the automatic grouting and pressurizing unit are controlled to remain unchanged; The automatic grouting booster unit is in the state of not replenishing fluid flow: The control center is used to control the valve opening of the automatic throttling unit to be the maximum value when the parameter deviation is greater than a fifth preset deviation threshold; When the parameter deviation is greater than the sixth preset deviation threshold and less than or equal to the fifth preset deviation threshold, the valve opening of the automatic throttling unit is controlled based on the parameter deviation; When the parameter deviation is less than or equal to the sixth preset deviation threshold, the valve opening of the automatic throttling unit is controlled to remain unchanged.

5. The pressure controlled cementing system according to claim 1, characterized in that: The automatic grouting and pressurizing unit comprises: a hydraulic component, an electrical control component and a piston pump; The electrical control component is electrically connected to the control center to receive a control instruction from the control center, and controls the hydraulic component to drive the piston pump to work and output a fluid flow based on the control instruction.

6. The managed pressure cementing system according to claim 5, characterized in that: The automatic grouting and pressurizing unit also includes a dynamic monitoring module to monitor the outlet pressure, outlet flow, temperature, voltage, and current data of the automatic grouting and pressurizing unit in real time, and to issue an early warning reminder when the monitoring data is abnormal.

7. The managed pressure cementing system according to claim 5, characterized in that: The automatic grouting and pressurizing unit further includes: a first human-computer interaction module; The first human-machine interaction module is used to control the automatic grouting and pressurization based on the operator's operating instructions, record and analyze the real-time monitoring data, and issue an alarm and perform fault diagnosis when the real-time monitoring data is abnormal; Correspondingly, the electrical control component is also used to control the hydraulic component to drive the piston pump to work and output fluid flow based on the control instruction of the first human-machine interaction module.

8. The managed pressure cementing system according to claim 1, characterized in that: The automatic throttling unit comprises: a modular straight-through skid and an automatic throttling skid assembly, wherein the automatic throttling skid assembly comprises at least one automatic throttling skid; The modular straight-through skid is arranged in parallel with the automatic throttling skid assembly; Furthermore, when the automatic throttling skid assembly includes two or more automatic throttling skids, the automatic throttling skids are arranged in parallel.

9. The managed pressure cementing system according to claim 8, characterized in that: The modular automatic throttling skid comprises: an electric control cabinet and an electric throttling valve arranged on the throttling pipeline; The electric control cabinet is used to control the valve opening of the electric throttle valve based on the control instruction of the control center.

10. The managed pressure cementing system according to claim 9, characterized in that: The automatic throttling skid further comprises: an air control cabinet, a first pressure sensor, an air control flat valve, a first needle valve, a manual valve, a second pressure sensor, a filter, a second needle valve and a mass flow meter which are sequentially arranged on the throttling pipeline; The gas control cabinet is used to control the opening and closing of the gas-controlled flat valve based on the control instructions of the control center; The electric throttle valve is arranged between the air-controlled flat valve and the first needle valve, and the pressure detected by the first pressure sensor is used as the measured pressure, and the mass flow meter is used to detect the fluid flow rate as the measured fluid flow rate.

11. The managed pressure cementing system according to claim 8, characterized in that: The modular straight-through skid includes: a main pipeline and a first pipeline and a second pipeline connected to the main pipeline, the first pipeline and the second pipeline are respectively used to communicate with the inlet and outlet of the throttling pipeline of the modular automatic throttling skid, and the main pipeline, the first pipeline and the second pipeline are respectively provided with flat valves for controlling the on and off of the pipelines.

12. The managed pressure cementing system according to claim 10, characterized in that: The automatic throttling unit further includes: a second human-computer interaction module; The second human-computer interaction module is used to control the automatic throttling unit based on the operator's operating instructions, record and analyze the real-time monitoring data, and issue an alarm and perform fault diagnosis when the real-time monitoring data is abnormal; Correspondingly, the gas control cabinet is also used to control the opening and closing of the gas-controlled flat valve based on the control instructions of the second human-machine interaction module; The electric control cabinet is also used to control the valve opening of the electric throttle valve based on the control instruction of the second human-machine interaction module.

13. The managed pressure cementing system according to claim 10, characterized in that: The control center is also used to provide a safety protection mode and / or an expert mode; The safety protection mode is used to give an early warning when the measured pressure is abnormal, and to perform one or more of the following controls: Control the electric throttle valve opening of the currently used automatic throttle skid to the maximum; When the flat valve of the modular direct-flow skid is a pneumatically controlled flat valve, the pneumatic flat valve of the modular direct-flow skid is controlled to open; When there are multiple automatic throttling skids, the pneumatically controlled flat valves of other automatic throttling skids are controlled to open; The expert mode is used to enable operation authority based on the authority instruction input by the operator, and when the operation authority is enabled, perform related operations based on the control instruction input by the operator, and the related operations include: conventional operations in non-expert mode and designated operations in expert mode; wherein the designated operations include: closing the electric-controlled throttle valve and / or the pneumatic-controlled flat valve.

14. The pressure controlled cementing system according to any one of claims 1 to 13, characterized in that: Also includes: Entry monitoring unit; The inlet monitoring unit is used to be connected to the wellhead entry pipe string to monitor the pressure and flow of the fluid entering the wellbore in real time.

15. The managed pressure cementing system according to claim 14, characterized in that: Also includes: Cementing pumps and drilling pumps; The drilling pump and cementing pump are respectively connected to the wellhead entry pipe string; The inlet measurement unit comprises: a first measurement pipeline and a first flow meter and a third pressure sensor arranged thereon, a second measurement pipeline and a second flow meter and a fourth pressure sensor arranged thereon; The first measuring pipeline is used to connect with the connecting pipeline between the cementing pump and the wellhead tubing string; the second measuring pipeline is used to connect with the connecting pipeline between the drilling pump and the wellhead tubing string.

16. A controlled pressure cementing method, characterized in that: include: Obtain target fluid parameters at the wellhead and corresponding measured fluid parameters; The fluid parameters include: pressure and / or fluid flow rate, and correspondingly, the measured fluid parameters include: the measured pressure at one end of the throttle valve of the automatic throttling unit close to the wellhead, and / or the fluid flow rate at the output end of the automatic throttling unit; Based on the parameter deviation between the target fluid parameter of the wellhead and the corresponding measured fluid parameter, the automatic throttling unit is controlled to adjust the opening of the valve, and / or the automatic grouting and pressurizing unit is controlled to adjust the output fluid flow rate to control the wellhead back pressure.

17. The controlled pressure cementing method according to claim 16, wherein: Based on the parameter deviation between the target fluid parameter at the wellhead and the corresponding measured fluid parameter, the automatic throttling unit is controlled to adjust the opening of the valve, and / or the automatic grouting and pressurizing unit is controlled to work, including: In the case where the measured fluid parameter is less than the target fluid parameter of the wellhead, based on the target fluid parameter of the wellhead and the parameter deviation range of the corresponding measured fluid parameter, the automatic throttling unit is controlled to adjust the valve opening of the throttling valve, and / or the automatic grouting and pressurizing unit is controlled to adjust the output fluid flow rate; In the case where the measured fluid parameter is greater than the target fluid parameter of the wellhead, if the automatic grouting and pressurization unit is in a state of supplementing fluid flow, the automatic throttling unit is controlled to adjust the valve opening of the throttling valve and / or the automatic grouting and pressurization unit is controlled to adjust the output fluid flow based on the target fluid parameter of the wellhead and the parameter deviation range of the corresponding measured fluid parameter; if the automatic grouting and pressurization unit is in a state of not supplementing fluid flow, the automatic throttling unit is controlled to adjust the valve opening of the throttling valve based on the parameter deviation range.

18. The controlled pressure cementing method according to claim 17, characterized in that: In the case where the measured fluid parameter is less than the target fluid parameter of the wellhead, based on the target fluid parameter of the wellhead and the parameter deviation range of the corresponding measured fluid parameter, the automatic throttling unit is controlled to adjust the valve opening of the throttling valve, and / or the automatic grouting and pressurizing unit is controlled to adjust the output fluid flow rate, including: in the case where the measured fluid parameter is less than the target fluid parameter of the wellhead: If the parameter deviation between the target fluid parameter at the wellhead and the corresponding measured fluid parameter is greater than a first preset deviation threshold, the throttle valve of the automatic throttling unit is controlled to be at a preset opening, the measured fluid parameter when the valve is at the preset opening is obtained, and based on the parameter deviation between the measured fluid parameter and the target fluid parameter at the wellhead, the automatic grouting and pressurization unit is controlled to increase the output fluid flow rate; If the parameter deviation is greater than a second preset deviation threshold and less than or equal to the first preset deviation threshold, the valve opening of the throttle valve is controlled based on the parameter deviation, or the valve opening of the throttle valve is controlled to remain unchanged, and the automatic grouting and boosting unit is controlled to increase the output fluid flow rate based on the parameter deviation; If the parameter deviation is less than or equal to the second preset parameter deviation, the valve opening of the automatic throttling unit and the fluid flow output by the automatic grouting and pressurizing unit are kept unchanged.

19. The controlled pressure cementing method according to claim 17, wherein: In the case where the measured fluid parameter is greater than the target fluid parameter of the wellhead, if the automatic grouting and pressurizing unit is in a state of supplementing fluid flow, based on the target fluid parameter of the wellhead and the parameter deviation range of the corresponding measured fluid parameter, the automatic throttling unit is controlled to adjust the valve opening of the throttling valve, and / or the automatic grouting and pressurizing unit is controlled to adjust the output fluid flow; if the automatic grouting and pressurizing unit is in a state where the fluid flow is not supplemented: the automatic throttling unit is controlled to adjust the valve opening of the throttling valve based on the parameter deviation range; including: in the case where the measured fluid parameter is greater than the target fluid parameter of the wellhead: The automatic grouting and boosting unit is in the state of supplementing fluid flow: If the parameter deviation between the target fluid parameter of the wellhead and the corresponding measured fluid parameter is greater than a third preset deviation threshold, based on the parameter deviation between the target fluid parameter of the wellhead and the corresponding measured fluid parameter, the automatic grouting and pressurizing unit is controlled to reduce the output fluid flow rate, and the valve opening of the automatic throttling unit is controlled to be the maximum value; If the parameter deviation is greater than a fourth preset deviation threshold and less than or equal to a third preset deviation threshold, the valve opening of the automatic throttling unit is controlled based on the parameter deviation, or the automatic grouting and pressurizing unit is controlled to reduce the output fluid flow rate; If the parameter deviation is less than or equal to the fourth preset parameter deviation threshold, the valve opening of the automatic throttling unit and the fluid flow rate output by the automatic grouting and pressurizing unit are controlled to remain unchanged; The automatic grouting booster unit is in the state of not replenishing fluid flow: If the parameter deviation is greater than a fifth preset deviation threshold, controlling the valve opening of the automatic throttling unit to be a maximum value; If the parameter deviation is greater than a sixth preset deviation threshold and less than or equal to a fifth preset deviation threshold, controlling the valve opening of the automatic throttling unit based on the parameter deviation; If the parameter deviation is less than or equal to the sixth preset deviation threshold, the valve opening of the automatic throttling unit is kept unchanged.

20. The controlled pressure cementing method according to claim 16, wherein: Based on the parameter deviation between the target fluid parameter at the wellhead and the measured fluid parameter, the automatic grouting and boosting unit is controlled to adjust the output fluid flow rate; including: Based on the parameter deviation between the target fluid parameter at the wellhead and the measured fluid parameter, the required output fluid flow rate of the automatic grouting and pressurizing unit is obtained; If the required output fluid flow rate is greater than the maximum output fluid flow rate of the automatic grouting and pressurizing unit, controlling the automatic grouting and pressurizing unit to perform fluid flow compensation at the maximum output fluid flow rate; If the required output fluid flow rate is not greater than the maximum output fluid flow rate of the automatic grouting and pressurizing unit, the automatic grouting and pressurizing system is controlled to perform fluid flow compensation with the required output fluid flow rate.

21. The controlled pressure cementing method according to claim 19, wherein: When the parameter deviation is greater than the second preset deviation threshold and less than or equal to the first preset deviation threshold, the parameter deviation is greater than the fourth preset deviation threshold and less than or equal to the third preset deviation threshold, and the parameter deviation is greater than the sixth preset deviation threshold and less than or equal to the fifth preset deviation threshold, the valve opening of the automatic throttling unit is controlled based on the parameter deviation; comprising: Judging whether the system is stable based on the measured deviation between the measured fluid parameters at the current moment and the measured fluid parameters at the previous moment; After the system is stable, the first stable parameter deviation after each adjustment is obtained based on the stabilized measured fluid parameters and the target fluid parameters at the wellhead; Based on the first stable parameter deviation after the current adjustment and the first stable parameter deviation after the last adjustment, the opening of the throttle valve to be adjusted is determined in combination with a PID algorithm.

22. The controlled pressure cementing method according to claim 19, wherein: If the parameter deviation is greater than the second preset deviation threshold and less than or equal to the first preset deviation threshold, and the parameter deviation is greater than the fourth preset deviation threshold and less than or equal to the third preset deviation threshold, the automatic grouting and boosting unit is controlled to adjust the output fluid flow based on the parameter deviation, including: Judging whether the system is stable based on the measured deviation between the measured fluid parameters at the current moment and the measured fluid parameters at the previous moment; After the system is stable, the second stable parameter deviation after each adjustment is obtained based on the stabilized measured fluid parameters and the target fluid parameters at the wellhead; Based on the second stable parameter deviation after the current adjustment and the second stable parameter deviation after the last adjustment, the fluid flow rate to be compensated of the automatic grouting and pressurizing unit is determined in combination with the PID algorithm.

23. The controlled pressure cementing method according to claim 21 or 22, characterized in that: When the fluid parameter is the fluid flow rate, the measured fluid parameters at the current moment are obtained, including: The measured fluid flow at preset moments is retained and updated, a maximum value and a minimum value are removed, the average value is obtained for filtering, and the average value after filtering is used as the measured fluid flow at the current moment.

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